josephjhaney

Well, I was considering a chain checker a while back, but just used the ruler method to check the chain, and all seemed well. I was recently at a performance bike, and picked one up anyway. Yeah, about that ruler method, the chain was over 1% worn. I didn't notice it, because it seems it wore mainly the inner/rollers, and didn't actually stretch all that much, when put side by side with the new chain, while you could see the old one was a bit longer, it wasn't by very much (far less than 1/8 of a length I would say) but the rollers were all kinds of sloppy.

I run a KMC 9 SL TI, for the rustproof factor, and I LOVE that chain, this chain went nearly 7,000 miles to wear this far, so if I keep getting close to that life out of them, I think they are well worth the extra cash.

This is just a heads up of my own experience. Have a great one!

Joe

DaveSSS 

The ruler method is the only correct way to measure chain elongation. A precision 12" rule is the best choice.

https://www.generaltools.com/Products...al_Rulers.aspx

Nearly all chain checker tools have a flawed method of measuring that exaggerates the wear by measuring over a short length and including the wear of a roller at each end of the measurement. Rollers wear as much as 10 times more than the pins/bushings, so adding that wear can result is a report of 1% elongation, when it's really half that.

Chain checkers will also report even more error due to the differences in roller diameter and clearances. A park tool is likely to report that a brand new Shimano or KMC chain is "worn" by .25%, even though it's pitch is perfect. That .25% false wear must be subtracted from future readings. Even then, the tool can still report twice the actual elongation. A Campy chain is more likely to read zero wear when new.

josephjhaney

I initially thought this method was better as well, but, if the rollers are that worn, then wouldn't they be not properly sitting on the cog as the chain goes around?

Joe

DaveSSS 

Roller wear has no effect on the chain pitch; the rollers self-center, even when worn. The rollers on most chains will last until the elongation reaches a true .5%, but there are exceptions. Campy chains, if well maintained may show very little elongation (properly measured with a rule) even after 6,000 miles of use. Despite the small elongation, the chain may be totally shot and may have worn one or more of the cogs enough that they will not mate with a new chain. With Campy chains, I use dial calipers and insert the internal measuring tips between the rollers. When new, the spacing will be about .200 inch. I change the chain (but don't trash it) when the roller spaicng increases to about .220 inch. I use 3-4 chains in a regular rotation and trash them when the roller spacing is about .240 inch. That might take 4-6,000 miles. By that time, the side clearance between the inner and outer plates will also be much greater. A new chain will have .004-.008 inch of clearance, but a well worn chain might meaure .013 or more.

fietsbob

FWIW, as all derailleur chains are now bushingless design,
Ie: the inner link is punched in, before the steel is tempered.
Likely while Hot.
It's the shoulder punched in that forms the edge contact that the roller rests on .
that.s where the wear concentrates.. a contact ring between roller and sideplate.

Bushingless chains are laterally flexible , thats what all modern shifting schemes require.

MudPie

I wish someone made a 13" precision rule. A 12" rule is about 1/16 to an 1/8 too short.

DaveSSS 

A 12" rule is not too short. Place one end on the edge of a pin. When new, the pin at the opposite end will be completely covered. When .5% elongation is reached, almost half of the pin that was covered will be exposed. If nearly all of the pin is exposed, you'd be up to 1% elongation.

Sixty Fiver

Get a multipurpose bike ruler... they have centre markers at the 1 and 12 and also have a bearing and cotter gauge and spoke measurement feature.

LesterOfPuppets

I have one of these 15" steel rules.

Jed19

+1. I bought one of those for about $3 a few years ago at Office Depot or Staples.

davidad

I use the Roloff chain checker until the chain gets a lot of wear on it. I then hang it on a wire and measure 4' of chain. I replace it when it shows nearly 1/4" in 4'.

josephjhaney

Wow, all GREAT info. I'm going to keep an eye on this chain, but I'll have it's replacement sitting in the drawer as well, I have three rear wheels with different cassettes on them to rotate out for different riding, one is very light, 12-25 dura ace, the other is a 12-25 ultegra, mid weight with a tire more suited for wear than for speed, and the third is a 12-23 ultegra on a 105 hub with a nice 32 spoke count, for day to day riding/commuting. It has a schwalabe Durano tire, for maximum puncture resistance. I rotate these out, and noticed that on both the old chain and the new one they are all working without issue, so I'm glad my wear was not enough to have an effect on my cassettes.

I think I'm going to get one of the bicycle rulers as well, can't have too many bike tools

Joe

jimmuller 

If you want a 13" ruler a 12" ruler is 1" too short.